Optical disk unit

ABSTRACT

An optical disk unit presets a value θ 1  which prescribes an optimum recording pulse width of a light source for a case where the optical disk is rotated at a predetermined linear velocity on a track located at a predetermined radial position on the optical disk, and an optimum power ratio ΔP of an extra pulse at a leading portion of the recording pulse where power is increased. Information is recorded on the optical disk while controlling a light emission waveform of the light source based on a value θ 1  (v) which prescribes the recording pulse width, a power ratio ΔP(v) and an optimum recording power Pwo(v) which are successively calculated.

BACKGROUND OF THE INVENTION

[0001] This application claims the benefit of a Japanese PatentApplication No. 2000-161357 filed May 31, 2000, in the Japanese PatentOffice, the disclosure of which is hereby incorporated by reference.

[0002] 1. Field of the Invention

[0003] The present invention generally relates to optical disk units,and more particularly to an optical disk unit which uses a writable(recordable) or rewritable optical disk.

[0004] 2. Description of the Related Art

[0005] Generally, in an optical disk called a compact disk (CD), aspiral track is formed at a constant liner density from an innerperiphery to an outer periphery of the disk. In addition, informationcan be recorded in a CD called a CD-Recordable (CD-R). When recordingthe information on the CD-R, the information is also recorded at aconstant linear density on a spiral track which is formed from the innerperiphery to the outer periphery of the CD-R. Information is similarlyrecorded on a CD called a CD-Rewritable (CD-RW), that is, at a constantlinear density on a spiral track which is formed from the innerperiphery to the outer periphery of the CD-RW. The information isrewritable in the case of the CD-RW.

[0006] Recording and reproducing systems used to record information onand reproduce information from the optical disks such as the CD-R andthe CD-RW can generally by categorized into a constant linear velocity(CLV) system and a constant angular velocity (CAV) system. There is alsoa recording and reproducing system called a zone constant linearvelocity (ZCLV) system which is a modification of the CLV system. Forexample, such recording and reproducing systems are proposed in JapaneseLaid-Open Patent Applications No. 11-296858, 2000-11384, No. 2000-48484,No. 7-21585, No. 9-231580, No. 9-270129, No. 10-79124, and No. 11-66726.

[0007] According to the CLV system, the optical disk is rotated at aconstant linear velocity. Hence, although data management and rotationalvelocity control become slightly complex, it is possible to maximize arecording capacity by the CLV system. On the other hand, according tothe CAV system, the optical disk is rotated at a constant angularvelocity, that is, at a constant number of revolutions. For this reason,the data management and the rotational velocity control become simple,but the recording capacity is slightly sacrificed according to the CAVsystem. According to the ZCLV system, a recording surface of the opticaldisk is divided into a plurality of zones, and the linear velocity ismaintained constant within each of the zones, similarly to the CLVsystem. The ZCLV system changes the rotational velocity for each zone sothat the rotational velocity increases towards the outer periphery ofthe optical disk.

[0008] When recording information on the recordable or rewritableoptical disks such as the CD-R and the CDRW, the CAV system or the ZCLVsystem is employed by placing priority on the ease of the rotationcontrol of the optical disk. Particularly, the CAV system is desirablein order to satisfy the recent demands to improve the recording velocity(rate) and realize a recording such as a 20-times speed recording.

[0009] However, when the optical disk in conformance with the CLVsystem, such as the CD-R and the CD-RW, is rotated according to the CAVsystem, the linear velocity increases as a radial position on theoptical disk moves towards the outer periphery of the optical disk. Butsince an optimum recording laser power increases proportionally to thelinear velocity, it is not possible to record the information at anoptimum recording power in an outer peripheral portion of the opticaldisk if the recording power is maintained constant.

[0010] In addition, a setting of a write strategy (light emissionwaveform of a semiconductor laser) shown in FIG. 1 with respect to theCD-R does not lead to an ideal recording mark on the optical disk asshown in FIG. 2A when a high-speed write is carried out. Instead, theactual recording mark on the optical disk typically becomes as shown inFIG. 2B when the high-speed write is carried out. In FIG. 2B, a portion{circle over (1)} corresponds to a shape which is formed due toinsufficient heat transfer to the optical disk immediately after theirradiation of the laser beam on the optical disk starts, and a portion{circle over (2)} corresponds to a shape which is formed due toinsufficient heat release immediately after the irradiation of the laserbeam on the optical disk ends.

[0011] Accordingly, as shown in FIG. 1, with respect to a recordingclock period T at each linear velocity, the laser power at a leadingportion of a recording pulse is set larger than at a trailing portion ofthe recording pulse, in a form of an extra pulse, and a recording pulsewidth is set narrower than the actual width which is to be written. Withregard to the recording clock period T, 1T denotes a 1 times-speedreproduction of 1.2 to 1.4 m/s, for example, and amounts to 231.4 ns.Such a modification of the write strategy is mainly made by changing avalue θ₁ which prescribes the recording pulse width n−θ₁T indicated by{circle over (1)} in FIG. 1, and/or changing a power ΔP of the extrapulse indicated by {circle over (4)} in FIG. 1, where n denotes aninteger from 2 to 11 of an EFM signal. In FIG. 1, a portion {circle over(2)} corresponds to a pulse width αT, and a portion {circle over (3)}corresponds to a recording power Pw.

[0012] In addition, FIG. 3 shows a write strategy with respect to theCD-RW using multi-recording pulses. In the case of the recent high-speedwrite with respect to the optical disk, a peak pulse width at a leadingportion of the multi-recording pulses is set wide with respect to therecording clock period T for each linear velocity, so as to facilitateheat transfer to the optical disk immediately after the irradiation ofthe laser beam on the optical disk starts. Moreover, an OFF-pulse widthat a last portion of the multi-recording pulses is set narrow so as toadjust the remaining heat effect. In order to form an ideal recordingmark on the optical disk, such a modification of the write strategy ismainly made by changing a peak pulse width θ₂ at a portion {circle over(1)} shown in FIG. 3, and/or changing an OFF-pulse width xn at a portion{circle over (2)} shown in FIG. 3. In FIG. 3, a portion {circle over(3)} corresponds to an intermediate pulse width.

[0013] In any case, the setting of the write strategy is changed foreach recording linear velocity. For this reason, in the case of theCD-R, there is a problem in that the recording cannot be made under anoptimum recording condition if the value θ₁ which prescribes therecording pulse width n−θ₁T d the power ΔP of the extra pulse remainconstant. In the case of the CD-RW, there is a problem in that therecording cannot be made under an optimum recording condition if thepeak pulse width θ₂ and the OFF-pulse width xn remain constant.

[0014] Such problems similarly occur when rotating the optical disk,such as the CD-R and the CD-RW, according to the ZCLV system.

SUMMARY OF THE INVENTION

[0015] Accordingly, it is a general object of the present invention toprovide a novel and useful optical disk unit in which the problemsdescribed above are eliminated.

[0016] Another and more specific object of the present invention is toprovide an optical disk unit which can always record information withrespect to a recordable or rewritable optical disk at an optimumrecording condition, using the CAV system or the ZCLV system which canimprove the recording velocity as compared to the CLV system.

[0017] Still another object of the present invention is to provide anoptical disk unit which can cope with a case where an optical disk usedhas a low recording sensitivity and/or a case where a light source usedhas a low maximum power output.

[0018] A further object of the present invention is to provide anoptical disk unit which can cope with a case where optical disks usedare manufactured by different manufacturers.

[0019] Another object of the present invention is to provide an opticaldisk unit which can cope with a case where optical disks used aremanufactured by the same manufacturer but are of different types.

[0020] Still another object of the present invention is to provide anoptical disk unit comprising a light source irradiating a light beam ona recordable optical disk; rotationally driving means for rotating theoptical disk; setting means for presetting a value θ₁ which prescribesan optimum recording pulse width of the light source for a case wherethe optical disk is rotated at a predetermined linear velocity on atrack located at a predetermined radial position on the optical disk,and an optimum power ratio ΔP of an extra pulse at a leading portion ofthe recording pulse where power is increased; test write means forcarrying out a test write a predetermined number of times prior torecording, on the track located at the predetermined radial position onthe optical disk, by driving the light source at a recording power whichdiffers for each step, while rotating the optical disk by therotationally driving means at the predetermined linear velocity, usingthe value θ₁ which prescribes the optimum recording pulse width theoptimum power ratio ΔP of the extra pulse which are preset by thesetting means; reference optimum recording power determination means forreproducing data recorded by the test write carried out by the testwrite means, and determining an optimum recording power Pwo based oncharacteristic values of the reproduced data; recording rotation controlmeans for rotating the optical disk by the rotationally driving means ata predetermined number of revolutions when recording information; lightemission waveform updating computation means for successivelycalculating a value θ₁ (v) which prescribes the recording pulse width, apower ratio ΔP(v) and an optimum recording power Pwo(v), depending on anarbitrary linear velocity v at a recording target track which is to berecorded, by adding corrections dependent on the arbitrary linearvelocity v with respect to the value θ₁ which prescribes the optimumrecording pulse width when recording the information, the power ratio ΔPand the optimum recording power Pwo which is determined by the referenceoptimum recording power determination means; and recording light sourcecontrol means for recording the information while controlling a lightemission waveform of the light source based on the value θ₁ (v) whichprescribes the recording pulse width, the power ratio ΔP(v) and theoptimum recording power Pwo(v) which are successively calculated by thelight emission waveform update computation means. According to theoptical disk unit of the present invention, it is possible to improvethe recording velocity because the optical disk is basically rotated atthe predetermined number of revolutions in conformance with the CAVsystem during the recording. Furthermore, since the value θ₁ (v) whichprescribes the recording pulse width, the power ratio ΔP(v) and theoptimum recording power Pwo(v) are successively calculated, and therecording is carried out while controlling the light emission waveformof the light source based on the calculated values, it is possible toalways record the information under a stable recording condition inconformance with the CAV system, even if the linear velocity during therecording changes.

[0021] The optical disk unit may further comprise judging means forjudging whether or not the optimum recording power Pwo(v) calculated bythe light emission waveform update computation means depending on thearbitrary linear velocity v on the track reaches a predetermined upperlimit value of an output power of the light source, where the recordingrotation control means switches rotation to rotate the optical disk bythe rotationally driving means at a constant linear velocity in a trackregion in which the judging means judges that the optimum recordingpower Pwo(v) reaches the predetermined upper limit value of the outputpower of the light source. According to the optical disk unit of thepresent invention, a decision is made to determine whether or not theoptimum recording power Pwo(v) reaches the maximum output Pwmax of thelight source. The recording is carried out in conformance with the CAVsystem at the original predetermined number of revolutions in a trackregion in which the maximum output Pwmax is not exceeded. On the otherhand, in a track region in which the maximum output Pwmax is reached orexceeded, the recording is carried out in conformance with the CLVsystem at the constant linear velocity which introduces no change in thelinear velocity v. For this reason, it is possible to continue therecording at the maximum output of the light source, and it is thuspossible to cope with cases where the light source used has a lowmaximum output for the recording power and the optical disk used has alow recording sensitivity, by a minimum required decrease in therecording velocity.

[0022] A further object of the present invention is to provide anoptical disk unit for recording information on a recordable optical diskwhich has a recording surface divided into a plurality of zones in aradial direction thereof, by rotating the optical disk at a rotationalvelocity which is different for each zone so that a linear velocitywithin each zone is approximately constant, comprising a light sourceirradiating a light beam on the optical disk; rotationally driving meansfor rotating the optical disk; setting means for presetting a value θ₁which prescribes an optimum recording pulse width of the light sourcefor a case where the optical disk is rotated at a predetermined linearvelocity on a track located at a predetermined radial position on theoptical disk, and an optimum power ratio ΔP of an extra pulse at aleading portion of the recording pulse where power is increased; testwrite means for carrying out a test write a predetermined number oftimes prior to recording, on the track located at the predeterminedradial position on the optical disk, by driving the light source at arecording power which differs for each step, while rotating the opticaldisk by the rotationally driving means at the predetermined linearvelocity, using the value θ₁ which prescribes the optimum recordingpulse width the optimum power ratio ΔP of the extra pulse which arepreset by the setting means; reference optimum recording powerdetermination means for reproducing data recorded by the test writecarried out by the test write means, and determining an optimumrecording power Pwo based on characteristic values of the reproduceddata; recording rotation control means for rotating the optical disk bythe rotationally driving means at a rotational velocity which isdifferent for each zone so that a predetermined linear velocity isapproximately obtained within each zone when recording information;light emission waveform updating computation means for successivelycalculating a value θ₁ (v) which prescribes the recording pulse width, apower ratio ΔP(v) and an optimum recording power Pwo(v), depending on anarbitrary linear velocity v at a recording target zone which is to berecorded, by adding corrections dependent on the arbitrary linearvelocity v with respect to the value θ₁ which prescribes the optimumrecording pulse width when recording the information, the power ratio ΔPand the optimum recording power Pwo which is determined by the referenceoptimum recording power determination means; and recording light sourcecontrol means for recording the information while controlling a lightemission waveform of the light source based on the value θ₁ (v) whichprescribes the recording pulse width, the power ratio ΔP(v) and theoptimum recording power Pwo(v) which are successively calculated by thelight emission waveform update computation means. According to theoptical disk unit of the present invention, the setting of the value θ₁which prescribes the optimum recording pulse width and the power ratioΔP and the determination of the optimum recording power Pwo only need tobe carried out once based on a PCA which has the predetermined radialposition and in which the linear velocity is the predetermined linearvelocity. Thereafter, the value θ₁ (v) which prescribes the recordingpulse width, the power ratio ΔP(v) and the optimum recording powerPwo(v) can be successively calculated and set depending on the linearvelocity v of the target recording zone, so that it is possible toalways record the information under a stable recording condition, evenwith respect to the ZCLV system.

[0023] The optical disk unit may further comprise judging means forjudging whether or not the optimum recording power Pwo(v) calculated bythe light emission waveform update computation means depending on thearbitrary linear velocity v on the track reaches a predetermined upperlimit value of an output power of the light source, where the recordingrotation control means switches rotation to rotate the optical disk bythe rotationally driving means at a linear velocity with which thepredetermined upper limit value becomes the optimum recording powerPwo(v) in a recording zone region in which the judging means judges thatthe optimum recording power Pwo(v) reaches the predetermined upper limitvalue of the output power of the light source. According to the opticaldisk unit of the present invention, a decision is made to determinewhether or not the optimum recording power Pwo(v) reaches the maximumoutput Pwmax of the light source. The recording is carried out inconformance with the CLV system at the original predetermined linearvelocity in a recording zone region in which the maximum output Pwmax isnot exceeded. On the other hand, in a recording zone region in which themaximum output Pwmax is reached or exceeded, the recording is carriedout in conformance with the ZCLV system at the constant linear velocitywhich introduces no change in the linear velocity v within eachrecording zone. For this reason, it is possible to continue therecording at the maximum output of the light source, and it is thuspossible to cope with cases where the light source used has a lowmaximum output for the recording power and the optical disk used has alow recording sensitivity, by a minimum required decrease in therecording velocity.

[0024] The optical disk unit may further comprise manufacturer judgingmeans for judging a manufacturer of the optical disk based on anidentification code prerecorded on the optical disk, where the lightemission waveform updating computation means calculates the value θ₁ (v)which prescribes the recording pulse width, the power ratio ΔP(v) andthe optimum recording power Pwo (v), depending on the arbitrary linearvelocity v and coefficients which are preset for each manufacturerjudged by the manufacturer judging means. According to the optical diskunit of the present invention, the media manufacturer of the opticaldisk used is judged based on the identification code prerecorded on theoptical disk, and the value θ₁ (v) which prescribes the recording pulsewidth, the power ratio ΔP(v) and the optimum recording power Pwo(v) arerespectively calculated by taking into consideration the coefficients ofthe judged media manufacturer. The coefficients are preset for each ofthe media manufacturers. As a result, it is possible to appropriatelycope with the differences among the media manufacturers of the opticaldisk which is used by the optical disk unit.

[0025] Furthermore, the manufacturer judging means may further judges atype of the optical disk, and the light emission waveform updatingcomputation means uses for the calculation values which are obtained bymultiplying constants to corresponding ones of the coefficientsdepending on the type of the optical disk judged by the manufacturerjudging means. According to the optical disk unit of the presentinvention, by also judging the type of the optical disk, the value θ₁(v) which prescribes the recording pulse width, the power ratio ΔP(v)and the optimum recording power Pwo(v) are calculated by taking intoconsideration the values which are obtained by multiplying thecoefficients which differ depending on the type of the optical disk withrespect to the corresponding coefficients which are preset for eachjudged media manufacturer. Consequently, it is possible to appropriatelycope with optical disks manufactured by different media manufacturers aswell as different type of optical disks.

[0026] Another object of the present invention is to provide an opticaldisk unit comprising a light source irradiating a light beam on arewritable optical disk; rotationally driving means for rotating theoptical disk; setting means for presetting an optimum peak pulse widthθ₂ at a leading portion of multi-recording pulses of the light sourceand an OFF-pulse width xn at a last portion of the multi-recordingpulses for a case where the optical disk is rotated at a predeterminedlinear velocity on a track located at a predetermined radial position onthe optical disk; test write means for carrying out a test write apredetermined number of times prior to recording, on the track locatedat the predetermined radial position on the optical disk, by driving thelight source at a recording power which differs for each step, whilerotating the optical disk by the rotationally driving means at thepredetermined linear velocity, using the peak pulse width θ₂ and theOFF-pulse width xn which are preset by the setting means; referenceoptimum recording power determination means for reproducing datarecorded by the test write carried out by the test write means, anddetermining an optimum recording power Pwo based on characteristicvalues of the reproduced data; recording rotation control means forrotating the optical disk by the rotationally driving means at apredetermined number of revolutions when recording information; lightemission waveform updating computation means for successivelycalculating a peak pulse width θ₂ (v), an OFF-pulse width xn(v) and anoptimum recording power Pwo(v), depending on an arbitrary linearvelocity v at a recording target track which is to be recorded, byadding corrections dependent on the arbitrary linear velocity v withrespect to the peak pulse width θ₂, the OFF-pulse width xn and theoptimum recording power Pwo which is determined by the reference optimumrecording power determination means; and recording light source controlmeans for recording the information while controlling a light emissionwaveform of the light source based on the peak pulse width θ₂ (v), theOFF-pulse width xn(v) and the optimum recording power Pwo(v) which aresuccessively calculated by the light emission waveform updatecomputation means. According to the optical disk unit of the presentinvention, it is possible to improve the recording velocity because theoptical disk is basically rotated at the predetermined number ofrevolutions in conformance with the CAV system during the recording.Furthermore, since the peak pulse width θ₂ (V), the OFF-pulse width xn(v) and the optimum recording power Pwo(v) are successively calculated,and the recording is carried out while controlling the light emissionwaveform of the light source based on the calculated values, it ispossible to always record the information under a stable recordingcondition in conformance with the CAV system, even if the linearvelocity during the recording changes.

[0027] The optical disk unit may further comprise judging means forjudging whether or not the optimum recording power Pwo(v) calculated bythe light emission waveform update computation means depending on thearbitrary linear velocity v on the track reaches a predetermined upperlimit value of an output power of the light source, where the recordingrotation control means switches rotation to rotate the optical disk bythe rotationally driving means at a constant linear velocity in a trackregion in which the judging means judges that the optimum recordingpower Pwo(v) reaches the predetermined upper limit value of the outputpower of the light source. According to the optical disk unit of thepresent invention, a decision is made to determine whether or not theoptimum recording power Pwo(v) reaches the maximum output Pwmax of thelight source. The recording is carried out in conformance with the CAVsystem at the original predetermined number of revolutions in a trackregion in which the maximum output Pwmax is not exceeded. On the otherhand, in a track region in which the maximum output Pwmax is reached orexceeded, the recording is carried out in conformance with the CLVsystem at the constant linear velocity which introduces no change in thelinear velocity v. For this reason, it is possible to continue therecording at the maximum output of the light source, and it is thuspossible to cope with cases where the light source used has a lowmaximum output for the recording power and the optical disk used has alow recording sensitivity, by a minimum required decrease in therecording velocity.

[0028] Still another object of the present invention is to provide anoptical disk unit for recording information on a rewritable optical diskwhich has a recording surface divided into a plurality of zones in aradial direction thereof, by rotating the optical disk at a rotationalvelocity which is different for each zone so that a linear velocitywithin each zone is approximately constant, comprising a light sourceirradiating a light beam on the optical disk; rotationally driving meansfor rotating the optical disk; setting means for presetting a peak pulsewidth θ₂ at a leading portion of multi-recording pulses of the lightsource and an OFF-pulse width xn at a last portion of themulti-recording pulses for a case where the optical disk is rotated at apredetermined linear velocity on a track located at a predeterminedradial position on the optical disk; test write means for carrying out atest write a predetermined number of times prior to recording, on thetrack located at the predetermined radial position on the optical disk,by driving the light source at a recording power which differs for eachstep, while rotating the optical disk by the rotationally driving meansat the predetermined linear velocity, using the peak pulse width θ₂ andthe OFF-pulse width xn which are preset by the setting means; referenceoptimum recording power determination means for reproducing datarecorded by the test write carried out by the test write means, anddetermining an optimum recording power Pwo based on characteristicvalues of the reproduced data; recording rotation control means forrotating the optical disk by the rotationally driving means at arotational velocity which is different for each zone so that apredetermined linear velocity is approximately obtained within each zonewhen recording information; light emission waveform updating computationmeans for successively calculating a peak pulse width θ₂ (v), anOFF-pulse width xn (v) and an optimum recording power Pwo(v), dependingon an arbitrary linear velocity v at a recording target zone which is tobe recorded, by adding corrections dependent on the arbitrary linearvelocity v with respect to the peak pulse width θ₂, the OFF-pulse widthxn and the optimum recording power Pwo which is determined by thereference optimum recording power determination means; and recordinglight source control means for recording the information whilecontrolling a light emission waveform of the light source based on thepeak pulse width θ₂ (v), the OFF-pulse width xn(v) and the optimumrecording power Pwo(v) which are successively calculated by the lightemission waveform update computation means. 10. The optical disk unit asclaimed in claim 13, further comprising judging means for judgingwhether or not the optimum recording power Pwo(v) calculated by thelight emission waveform update computation means depending on thearbitrary linear velocity v on the track reaches a predetermined upperlimit value of an output power of the light source, where the recordingrotation control means switches rotation to rotate the optical disk bythe rotationally driving means at a linear velocity with which thepredetermined upper limit value becomes the optimum recording powerPwo(v) in a recording zone region in which the judging means judges thatthe optimum recording power Pwo(v) reaches the predetermined upper limitvalue of the output power of the light source. According to the opticaldisk unit of the present invention, the setting of the peak pulse widthθ₂ (v) and the OFF-pulse width xn(v) and the determination of theoptimum recording power Pwo only need to be carried out once based on aPCA which has the predetermined radial position and in which the linearvelocity is the predetermined linear velocity. Thereafter, the peakpulse width θ₂ (V), the OFF-pulse width xn(v) and the optimum recordingpower Pwo(v) can be successively calculated and set depending on thelinear velocity v of the target recording zone, so that it is possibleto always record the information under a stable recording condition,even with respect to the ZCLV system.

[0029] The optical disk unit may further comprise judging means forjudging whether or not the optimum recording power Pwo(v) calculated bythe light emission waveform update computation means depending on thearbitrary linear velocity v on the track reaches a predetermined upperlimit value of an output power of the light source, where the recordingrotation control means switches rotation to rotate the optical disk bythe rotationally driving means at a linear velocity with which thepredetermined upper limit value becomes the optimum recording powerPwo(v) in a recording zone region in which the judging means judges thatthe optimum recording power Pwo(v) reaches the predetermined upper limitvalue of the output power of the light source. According to the opticaldisk unit of the present invention, a decision is made to determinewhether or not the optimum recording power Pwo(v) reaches the maximumoutput Pwmax of the light source. The recording is carried out inconformance with the CLV system at the original predetermined linearvelocity in a recording zone region in which the maximum output Pwmax isnot exceeded. On the other hand, in a recording zone region in which themaximum output Pwmax is reached or exceeded, the recording is carriedout in conformance with the ZCLV system at the constant linear velocitywhich introduces no change in the linear velocity v within eachrecording zone. For this reason, it is possible to continue therecording at the maximum output of the light source, and it is thuspossible to cope with cases where the light source used has a lowmaximum output for the recording power and the optical disk used has alow recording sensitivity, by a minimum required decrease in therecording velocity.

[0030] The optical disk unit may further comprise manufacturer judgingmeans for judging a manufacturer of the optical disk based on anidentification code prerecorded on the optical disk, where the lightemission waveform updating computation means calculates the peak pulsewidth θ₂ (v), the OFF-pulse width xn (v) and the optimum recording powerPwo(v), depending on the arbitrary linear velocity v and coefficientswhich are preset for each manufacturer judged by the manufacturerjudging means. According to the optical disk unit of the presentinvention, the media manufacturer of the optical disk used is judgedbased on the identification code prerecorded on the optical disk, andthe peak pulse width θ₂(V), the OFF-pulse width xn(v) and the optimumrecording power Pwo(v) are respectively calculated by taking intoconsideration the coefficients of the judged media manufacturer. Thecoefficients are preset for each of the media manufacturers. As aresult, it is possible to appropriately cope with the differences amongthe media manufacturers of the optical disk which is used by the opticaldisk unit.

[0031] Furthermore, the manufacturer judging means may further judges atype of the optical disk, and the light emission waveform updatingcomputation means uses for the calculation values which are obtained bymultiplying constants to corresponding ones of the coefficientsdepending on the type of the optical disk judged by the manufacturerjudging means. According to the optical disk unit of the presentinvention, by also judging the type of the optical disk, the peak pulsewidth θ₂ (v), the OFF-pulse width xn (v) and the optimum recording powerPwo(v) are calculated by taking into consideration the values which areobtained by multiplying the coefficients which differ depending on thetype of the optical disk with respect to the corresponding coefficientswhich are preset for each judged media manufacturer. Consequently, it ispossible to appropriately cope with optical disks manufactured bydifferent media manufacturers as well as different type of opticaldisks.

[0032] Other objects and further features of the present invention willbe apparent from the following detailed description when read inconjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0033]FIG. 1 is a time chart for explaining a write strategy for a CD-R;

[0034]FIGS. 2A and 2B are diagrams for explaining shapes of a recordingmark;

[0035]FIG. 3 is a timing chart for explaining a write strategy for aCD-RW;

[0036]FIG. 4 is a system block diagram showing a general structure of afirst embodiment of an optical disk unit according to the presentinvention;

[0037]FIG. 5 is a diagram for explaining an area structure of an opticaldisk;

[0038]FIG. 6 is a flow chart for generally explaining a recordingprocess of the first embodiment;

[0039]FIG. 7 is a flow chart for explaining a recording process of asecond embodiment of the optical disk unit according to the presentinvention;

[0040]FIG. 8 is a flow chart for explaining a recording process of athird embodiment of the optical disk unit according to the presentinvention;

[0041]FIG. 9 is a flow chart for explaining a recording process of afourth embodiment of the optical disk unit according to the presentinvention;

[0042]FIG. 10 is a flow chart for explaining a recording process of afifth embodiment of the optical disk unit according to the presentinvention;

[0043]FIG. 11 is a flow chart for explaining a recording process of asixth embodiment of the optical disk unit according to the presentinvention;

[0044]FIG. 12 is a flow chart for explaining a recording process of aseventh embodiment of the optical disk unit according to the presentinvention;

[0045]FIG. 13 is a flow chart for explaining a recording process of aneighth embodiment of the optical disk unit according to the presentinvention;

[0046]FIG. 14 is a flow chart for explaining a recording process of aninth embodiment of the optical disk unit according to the presentinvention; and

[0047]FIG. 15 is a flow chart for explaining a recording process of atenth embodiment of the optical disk unit according to the presentinvention;

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0048] A description will be given of a first embodiment of an opticaldisk unit according to the present invention, by referring to FIGS. 4through 6. In this embodiment, the present invention is applied to acase where information is recorded on and/or reproduced from arecordable optical disk, that is, a CD-R.

[0049]FIG. 4 is a system block diagram showing a general structure ofthis first embodiment of the optical disk unit (optical disk drive). InFIG. 4, a spindle motor 2 forms a rotationally driving means forrotating an optical disk 1. The spindle motor 2 is controlled to aconstant linear velocity (CLV) or to a constant number of revolutions(CAV), by a motor driver 3 and a servo circuit 4. An optical pickup 5has a known structure including a light source which is formed by asemiconductor laser, an optical system, a focusing actuator, a trackingactuator, a light receiving element, a position sensor and the likewhich are not shown in FIG. 4. The optical pickup 5 irradiates a laserbeam on a recording surface of the optical disk 1.

[0050] The optical pickup 5 is movable in a sledge direction, that is,in a radial direction of the optical disk 1, by a known seek motor (notshown). The motor driver 3 and the servo circuit 4 control a laser spotof the laser beam to a target position on the optical disk 1, based onsignals obtained from the focusing actuator, the tracking actuator, theseek motor, the light receiving element and the position sensor.

[0051] During a data reproduction, a reproduced signal obtained by theoptical pickup 5 is amplified and binarized by a read amplifier 6,before being input to a CD decoder 7 which carries out deinterleavingand error correction processes. After the deinterleaving and errorcorrection processes, reproduced data are input to a CD-ROM decoder 8which carries out an error correction for improving a reliability of thedata.

[0052] Thereafter, the data processed by the CD-ROM decoder 8 aretemporarily stored in a buffer RAM 10 by a buffer manager 9, and when asector data is obtained, the sector data is transferred to a hostcomputer (not shown) via the ATAPI/SCSI interface 11. In a case wherethe data read from the optical disk 1 are music data, the data outputfrom the CD decoder 7 are input to a digital-to-analog (D/A) converter12 to obtain an analog audio signal. This analog audio signal istransferred to the host computer via the ATAPI/SCSI interface 11, so asto make an audio output at the host computer.

[0053] On the other hand, during a data recording, data from the hostcomputer are received by the ATAPI/SCSI interface 11, and the receiveddata are temporarily stored in the buffer RAM 10 by the buffer manager9. The recording is started when a certain amount of data is stored inthe buffer RAM 10, but before starting the recording, the laser spot ispositioned to a write start position on the optical disk 1. The writestart position is obtained from a wobble signal which is prerecorded inthe form of a wave-shaped track on the optical disk 1. The wobble signalincludes absolute time information called ATIP, and the ATIP informationis obtained by the ATIP decoder 13.

[0054] In addition, a synchronizing signal generated from the ATIPdecoder 13 is input to the CD encoder 14, so that the data can bewritten at an accurate position. The data stored in the buffer RAM 10are subjected to processes, such as adding an error correction core andinterleaving, in a CD-ROM encoder 15 and a CD encoder 14, and arerecorded on the optical disk 1 via a laser control circuit 16 and theoptical pickup 5.

[0055] The optical disk unit also includes a microcomputer 20 forcontrolling operations of the various parts of the optical disk unitdescribed above, and for carrying out various functions which will bedescribed later. The microcomputer 20 has a known structure including aCPU 17, a ROM 18 and a RAM. Further, a non-volatile memory 21 is coupledto the CPU 17, and a RF peak and bottom detection circuit 22 is coupledbetween the read amplifier 6 and the laser control circuit 16.

[0056]FIG. 5 is a diagram showing an area structure of the optical disk1, that is, the CD-R. FIG. 5 shows a cross section taken along a radialdirection of the optical disk 1. The recording surface of the opticaldisk 1 includes, from the inner periphery towards the outer peripherythereof, a power calibration area (PCA) 31, a program memory area (PMA)32, a lead-in area 33, a program region 34, and a lead-out area 35. Theoptical disk unit adjusts the recording laser power by a so-calledoptimum power control (OPC) in the PCA 31 which is allocated for tracksat predetermined radial positions on the optical disk 1, and carries outthe data recording using the laser power which is obtained as a resultof the OPC.

[0057] During the data recording, the data received from the hostcomputer via the ATPI/SCSI interface 11 are temporarily stored in thebuffer RAM 10 before starting the recording. Excluding a case where theOPC result of the recording carried out in the past with respect to theoptical disk 1 is prestored in the nonvolatile memory 21, the OPC iscarried out in the PCA 31 of the optical disk 1 prior to the recording,so as to obtain the optimum recording power of the semiconductor laser.When carrying out the OPC, a test write amounting to a predeterminednumber of blocks (for example, fifteen blocks) corresponding to apredetermined number of times is carried out while increasing therecording power of the semiconductor laser for each one block (for eachone step) in the PCA 31 of the optical disk 1.

[0058] When carrying out the OPC, a data signal dependent on a reflectedlight received by the optical pickup 5 is amplified by the readamplifier 6, and is input to the peak and bottom detection circuit 22.The peak and bottom detection circuit 22 detects an upper peak level Pand a lower peak (bottom) level B of the data signal. The detected peaklevels A and B are subjected to an analog-to-digital (A/D) conversion toobtain digital peak levels. The CPU 17 or the like measures a β valuewhich describes an RF signal symmetry given by a formula β=(P+B)/(P−B)as indicated in the Orange Book Part II, based on the digital peaklevels, and determines a recording power which is used in a block wherethe β value is closest to a target value (for example, 0.04) as theoptimum recording power. When carrying out the OPC, the optical disk 1is rotated according to the CLV system so that the linear velocity isconstant. The optimum recording power is calculated in such a manner andis instructed to the laser control circuit 16. A write strategy withrespect to the optical disk 1, that is, the CD-R, is as shown in FIG. 1described above. Hence, a leading portion of a recording pulse includesan extra pulse having a power which is larger by a power ratio ΔP withrespect to a recording power Pw, and the recording pulse has a recordingpulse width n−θ₁T which is prescribed by a value θ₁.

[0059] Under the preconditions described above, when the recordableoptical disk 1 is loaded into the optical disk unit of this embodimentand a record (write) instruction is received from the host computer, theCPU 17 carries out the functions of a setting means, a test write means,a reference optimum recording power determination means, a recordingrotation control means, a light emission waveform updating computationmeans, and a recording light source control means. FIG. 6 is a flowchart for generally explaining a recording process of this firstembodiment.

[0060] First, in FIG. 6, when a step S1 issues a record instruction, astep S2 carries out a seek to a predetermined track which is at apredetermined radial position and is within the PCA 31 allocated to theinner peripheral region of the optical disk 1, by controlling theoptical pickup 5 prior to the recording. A step S3 controls the spindlemotor 2 to rotate the optical disk 1 at a predetermined linear velocityin conformance with the CLV system. For example, the predeterminedlinear velocity is v_(—)8×, and the optical disk 1 is rotated at an8-times speed (8×CLV). In this state, a step S4 sets the optimum powerratio ΔP of the extra pulse and the value θ₁ which prescribes theoptimum recording pulse width for prescribing the write strategy for theOPC. In other words, the step S4 sets the optimum power ratio ΔP_(—)8×of the extra pulse and the value θ_(1—)8× which prescribes the optimumrecording pulse width for the predetermined linear velocity 8×CLV. Suchdata which are set are prestored in the ROM 18, the non-volatile memory21 or the like, for example. The process carried out by the step S4prior to the recording corresponds to the function of the setting means.

[0061] In the state where the write strategy is set in this manner, astep S5 carries out the OPC while rotating the optical disk at thepredetermined linear velocity 8×CLV. That is, the OPC is carried out apredetermined number of times by driving the semiconductor laser at arecording power which differs for each step, while rotating the opticaldisk 1 by the spindle motor 2 at the predetermined linear velocity8×CLV, using the optimum power ratio ΔP_(—)8× of the extra pulse and thevalue θ_(1—)8× which prescribes the optimum recording pulse width forthe predetermined linear velocity 8×CLV. The process carried out by thestep S5 prior to the recording corresponds to the function of the testwrite means.

[0062] After the OPC ends, a step S6 reproduces the data recorded by thetest write of the OPC, and detects characteristic values related to thereproduced data, so as to determine an optimum recording power Pwo basedon the characteristic values. In this case, the optimum recording powerPwo is Pwo_(—)8×, and the process carried out by the step S6 correspondsto the function of the reference optimum recording power determinationmeans.

[0063] After these processes, the actual recording operation is carriedout. More particularly, a step S7 rotates the optical disk 1 by thespindle motor 2 at a predetermined number of revolutions in conformancewith the CAV system. The process carried out by the step S7 correspondsto the function of the recording rotation control means.

[0064] A step S8 successively calculates and sets a value θ₁ (v) whichprescribes the recording pulse width, a power ratio ΔP(v) and an optimumrecording power Pwo(v), depending on an arbitrary linear velocity v at arecording target track which is to be recorded by the optical pickup 5.In many cases, this arbitrary linear velocity v is greater than thelinear velocity v⁻8× for the PCA 31. The calculations are performed byadding corrections dependent on the arbitrary linear velocity v withrespect to the value θ_(1—)8× which prescribes the optimum recordingpulse width, the optimum power ratio ΔP_(—)8× of the extra pulse and theoptimum recording power Pwo_(—)8× which are set or determined by theprocess carried out prior to the recording. More particularly, theoptimum recording power Pwo(v), the value θ₁ (v) and the power ratioΔP(v) are defined by the following continuous functions (1), (2) and (3)of the arbitrary linear velocity v. The process carried out by the stepS8 corresponds to the function of the light emission waveform updatingcomputation means.

Pwo(v)=Pwo _(—)8×*sqrt(v/v _(—)8×)  (1)

θ₁(v)=θ_(1—)8×* (v _(—)8×/v)  (2)

ΔP(v)=ΔP _(—)8×*(v _(—)8×/v)  (3)

[0065] A step S9 carries out the recording operation with respect to theoptical disk 1 in conformance with the CAV system, while controlling thelight emission waveform (write strategy) of the semiconductor laser viathe laser control circuit 16 based on the value θ₁ (v) which prescribesthe recording pulse width, the power ratio ΔP(v) and the optimumrecording power Pwo(v) which are successively calculated and updated bythe step S8. The process carried out by the step S9 corresponds to thefunction of the recording light source control means.

[0066] Therefore, according to this embodiment, it is possible toimprove the recording velocity because the optical disk 1 is basicallyrotated at the predetermined number of revolutions in conformance withthe CAV system during the recording. Furthermore, since the value θ₁ (v)which prescribes the recording pulse width, the power ratio ΔP(v) andthe optimum recording power Pwo(v) are successively calculated, and therecording is carried out while controlling the light emission waveformof the semiconductor laser based on the calculated values, it ispossible to always record the information under a stable recordingcondition in conformance with the CAV system, even if the linearvelocity during the recording changes.

[0067] Next, a description will be given of a second embodiment of theoptical disk unit according to the present invention, by referring toFIG. 7. FIG. 7 is a flow chart for explaining a recording process ofthis second embodiment of the optical disk unit. In FIG. 7, those stepswhich are the same as those corresponding steps in FIG. 6 are designatedby the same reference numerals, and a description thereof will beomitted.

[0068] The general structure of this second embodiment of the opticaldisk unit, as well as the general structures of third through tenthembodiments of the optical disk unit according to the present inventionwhich will be described later, are the same as the general structure ofthe first embodiment of the optical disk unit shown in FIG. 4, and adescription thereof will be omitted.

[0069] In the first embodiment described above, the operation of theoptical disk unit is always in conformance with the CAV system whilerecording the information. Accordingly, as the target track movestowards the outer periphery of the optical disk 1, the linear velocity vincreases, and the optimum recording power Pwo(v) which is successivelycalculated also increases. For this reason, in a case where therecording sensitivity of the optical disk 1 is low and the optimumrecording power Pwo(v) which is originally determined by the OPC islarge, the optimum recording power Pwo(v) may exceed a predeterminedupper limit, that is, a maximum output Pwmax of the semiconductor laserdepending on the position of the track in the outer peripheral region ofthe optical disk 1. In such a case, the recording cannot be carried outat the optimum recording power Pwo(v).

[0070] This second embodiment takes into account such a case. Moreparticularly, during the actual recording operation, a step S10 shown inFIG. 7 decides whether or not the optimum recording power Pwo(v) whichis successively calculated is less than the maximum output Pwmax(predetermined upper limit value) of the semiconductor laser. If thedecision result in the step S10 is YES, a step S11 rotates the opticaldisk 1 in conformance with the CAV system, that is, continues therotation control of the step S7. Then, after the step S11, the step S9carries out the recording operation with respect to the optical disk 1in conformance with the CAV system.

[0071] On the other hand, if the decision result in the step S10 is NO,a step S12 stores the optimum recording power Pwo(v) (=Pwmax) and thepower ratio A P(v) and the value θ₁ (v) which prescribes the recordingpulse width in this state, as the write strategy of the semiconductorlaser, in order to record on the tracks subsequent to the target track.In addition, a step S13 switches the rotation of the spindle motor 2 torotate the optical disk 1 at the linear velocity v which becomesconstant in this state in conformance with the CLV system. A step S14carries out the recording operation with respect to the optical disk 1in conformance with the CLV system while controlling the light emissionwaveform (write strategy) of the semiconductor laser via the lasercontrol circuit 16, based on the stored optimum recording power Pwo(v)(=Pwmax) and the power ratio ΔP(v) and the value θ₁ (v) which prescribesthe recording pulse width in this state.

[0072] The process carried out by the step S10 corresponds to thefunction of the judging means, and the process carried out by the stepS13 corresponds to the function of the recording rotation control means.The process carried out by the step S14 corresponds to the function ofthe recording light source control means.

[0073] According to this embodiment, a decision is made to determinewhether or not the optimum recording power Pwo(v) reaches the maximumoutput Pwmax of the semiconductor laser. The recording is carried out inconformance with the CAV system at the original predetermined number ofrevolutions in a track region in which the maximum output Pwmax is notexceeded. On the other hand, in a track region in which the maximumoutput Pwmax is reached or exceeded, the recording is carried out inconformance with the CLV system at the constant linear velocity whichintroduces no change in the linear velocity v. For this reason, it ispossible to continue the recording at the maximum output of thesemiconductor laser, and it is thus possible to cope with cases wherethe semiconductor laser used has a low maximum output for the recordingpower and the optical disk used has a low recording sensitivity, by aminimum required decrease in the recording velocity.

[0074] Next, a description will be given of a third embodiment of theoptical disk unit according to the present invention, by referring toFIG. 8. FIG. 8 is a flow chart for explaining a recording process ofthis third embodiment of the optical disk unit. In FIG. 8, those stepswhich are the same as those corresponding steps in FIG. 6 are designatedby the same reference numerals, and a description thereof will beomitted.

[0075] This third embodiment is similar to the first embodiment, exceptthat this third embodiment rotates the optical disk 1 in conformancewith the ZCLV system in place of the CAV system during the recording.For example, the recording surface of the optical disk 1 is divided intoN=4 zones in the radial direction, and the recording is carried out byrotating the optical disk 1 in conformance with the CLV system so thatthat the rotational velocity (linear velocity) successively differs foreach of the zones from the inner periphery towards the outer periphery,as 8×, 12×, 16× and 20×.

[0076] The processes carried out by the steps S1 through S6 prior to therecording in this third embodiment which employs the ZCLV system, arethe same as those carried out in the first embodiment. In other words,the processes such as determination of the optimum recording power Pwoby the OPC are carried out once using the PCA 31.

[0077] When the processes carried out prior to the recording end, a stepS21 shown in FIG. 8 carries out a seek to a recording target zone N ofthe optical disk 1 by moving the optical pickup 5, so as to start therecording operation. A step S22 successively calculates and sets thevalue θ₁ (v) which prescribes the recording pulse width, the power ratioΔP(v) and the optimum recording power Pwo(v), depending on the arbitrarylinear velocity v related to the recording target zone N which is to berecorded by the optical pickup 5. The calculations are performed byadding corrections dependent on the arbitrary linear velocity v withrespect to the value θ_(1—)8× which prescribes the optimum recordingpulse width, the optimum power ratio ΔP_(—)8× of the extra pulse and theoptimum recording power Pwo_(—)8× which are set or determined by theprocess carried out prior to the recording. More particularly, theoptimum recording power Pwo(v), the value θ₁ (v) and the power ratioΔP(v) are defined by the continuous functions (1), (2) and (3) of thearbitrary linear velocity v described above. The process carried out bythe step S22 corresponds to the function of the light emission waveformupdating computation means.

[0078] A step S23 rotates the optical disk 1 by the spindle motor 2 inconformance with the CLV system so that the linear velocity v becomesthe predetermined linear velocity for the zone N. The process carriedout by the step S23 corresponds to the function of the recordingrotation control means.

[0079] A step S24 carries out the recording operation with respect tothe optical disk 1 in conformance with the CLV system, while controllingthe light emission waveform (write strategy) of the semiconductor laservia the laser control circuit 16 based on the value θ₁ (v) whichprescribes the recording pulse width, the power ratio ΔP(v) and theoptimum recording power Pwo(v) which are successively calculated andupdated by the step S22. The process carried out by the step S24corresponds to the function of the recording light source control means.

[0080] When carrying out the recording by rotating the optical disk 1 inconformance with the ZCLV system, if the process of the first embodimentwere carried out with respect to each zone, it would be necessary to setthe value θ₁ which prescribes the optimum recording pulse width and thepower ratio ΔP for each of the linear velocities amounting to the numberN of zones, and to determine the optimum recording power Pwo by the OPC.But according to this third embodiment, the setting of the value θ₁which prescribes the optimum recording pulse width and the power ratioΔP and the determination of the optimum recording power Pwo only need tobe carried out once based on the PCA 31 which has the predeterminedradial position and in which the linear velocity is the predeterminedlinear velocity 8×. Thereafter, the value θ₁ (v) which prescribes therecording pulse width, the power ratio ΔP(v) and the optimum recordingpower Pwo(v) can be successively calculated and set depending on thelinear velocity v of the target recording zone, so that it is possibleto always record the information under a stable recording condition,even with respect to the ZCLV system.

[0081] Next, a description will be given of a fourth embodiment of theoptical disk unit according to the present invention, by referring toFIG. 9. FIG. 9 is a flow chart for explaining a recording process ofthis fourth embodiment of the optical disk unit. In FIG. 9, those stepswhich are the same as those corresponding steps in FIGS. 6 through 8 aredesignated by the same reference numerals, and a description thereofwill be omitted.

[0082] In the third embodiment described above, the optimum recordingpower Pwo(v) calculated based on the continuous function (1) describedabove with respect to the recording zone in which the linear velocity is20×CLV, for example, may exceed the maximum output Pwmax (predeterminedupper limit value) of the semiconductor laser. In other words, it maynot be possible to record at the optimum recording power Pwo(v) in sucha case.

[0083] This fourth embodiment takes such a case into consideration. Moreparticularly, during the actual recording operation, the step S10 shownin FIG. 9 decides whether or not the optimum recording power Pwo(v)which is successively calculated is less than the maximum output Pwmax(predetermined upper limit value) of the semiconductor laser. If thedecision result in the step S10 is YES, the step S23 rotates the opticaldisk 1 in conformance with the ZCLV system, and the step S24 carries outthe recording operation with respect to the optical disk 1 inconformance with the CLV system within the zone.

[0084] On the other hand, if the decision result in the step S10 is NO,the step S12 stores the optimum recording power Pwo(v) (=Pwmax) and thepower ratio A P(v) and the value θ₁ (v) which prescribes the recordingpulse width in this state, as the write strategy of the semiconductorlaser, in order to record on the zones subsequent to the recordingtarget zone. In addition, a step S25 switches the rotation of thespindle motor 2 to rotate the optical disk 1 at the linear velocity vwhich becomes constant in this state in conformance with the CLV system.A step S26 carries out the recording operation with respect to theoptical disk 1 in conformance with the CLV system while controlling thelight emission waveform (write strategy) of the semiconductor laser viathe laser control circuit 16, based on the stored optimum recordingpower Pwo(v) (=Pwmax) and the power ratio ΔP(v) and the value θ₁ (v)which prescribes the recording pulse width in this state.

[0085] For example, if the optimum recording power Pwo(v) for the linearvelocity 16×CLV becomes the maximum output Pwmax of the semiconductorlaser, the recording operation with respect to the recording zone inwhich the linear velocity is 20×CLV is carried out by switching thelinear velocity to 16×CLV in the step S25. In addition, the optimumrecording power Pwo(v) is set to the maximum output Pwmax, and the powerratio ΔP(v) and the value θ₁ (v) which prescribes the recording pulsewidth for the linear velocity 16×CLV are set in the step S12.Furthermore, the recording operation is carried out in conformance withthe CLV system by the steps S25 and S26.

[0086] The process carried out by the step S10 corresponds to thefunction of the judging means, and the process carried out by the stepS25 corresponds to the function of the recording rotation control means.The process carried out by the step S26 corresponds to the function ofthe recording light source control means.

[0087] Therefore, according to this embodiment, a decision is made todetermine whether or not the optimum recording power Pwo(v) reaches themaximum output Pwmax of the semiconductor laser. The recording iscarried out in conformance with the CLV system at the originalpredetermined linear velocity in a recording zone region in which themaximum output Pwmax is not exceeded. On the other hand, in a recordingzone region in which the maximum output Pwmax is reached or exceeded,the recording is carried out in conformance with the ZCLV system at theconstant linear velocity which introduces no change in the linearvelocity v within each recording zone. For this reason, it is possibleto continue the recording at the maximum output of the semiconductorlaser, and it is thus possible to cope with cases where thesemiconductor laser used has a low maximum output for the recordingpower and the optical disk used has a low recording sensitivity, by aminimum required decrease in the recording velocity.

[0088] Next, a description will be given of a fifth embodiment of theoptical disk unit according to the present invention, by referring toFIG. 10. FIG. 10 is a flow chart for explaining a recording process ofthis fifth embodiment of the optical disk unit. In FIG. 10, those stepswhich are the same as those corresponding steps in FIG. 7 are designatedby the same reference numerals, and a description thereof will beomitted.

[0089] This fifth embodiment takes into consideration a manufacturer ofthe optical disk 1. Further, it is assumed for the sake of conveniencethat the manufacturer of the optical disk 1 is taken into considerationwhen using the second embodiment described above. Predeterminedcoefficients, optimum write strategies and the like which differ foreach manufacturer are prestored in a memory such as the ROM 18 and thenon-volatile memory 21 or, are successively updated and stored in thememory.

[0090] Under these preconditions, when the optical disk 1 is loaded intothe optical disk unit, a step S31 shown in FIG. 10 identifies amanufacture code recorded on the optical disk 1 to judge the mediamanufacturer. Normally, in the case of the optical disk 1 such as theCD-R, a lead-in-start-time recorded in the ATIP of the optical disk 1differs for each media manufacturer, and thus, the media manufacturercan be judged by reading this lead-in-start-time. The process carriedout by the step S31 corresponds to the function of a manufacturerjudging means.

[0091] After the media manufacturer is judged, a step S32 sets a writestrategy corresponding to the judged media manufacturer, by reading thewrite strategy from a write strategy table which stores write strategiesof various media manufacturers, optimized for a predetermined linearvelocity. After the step S32, the process advances to the step S2 andthe subsequent steps of the second embodiment described above.

[0092] When carrying out the successively updating and calculatingprocess for the actual recording operation, a step S33 is carried out inplace of the step S8. Basically, the step S33 is similar to the step S8,but differs in that the calculation is made using coefficients which aredifferent for each media manufacturer. In other words, the step S33performs the calculations by adding corrections dependent on thearbitrary linear velocity v and predetermined coefficients a through fwhich differ for each media manufacturer, with respect to the valueθ_(1—)8× which prescribes the optimum recording pulse width, the optimumpower ratio ΔP_(—)8× of the extra pulse and the optimum recording powerPwo_(—)8× which are set or determined by the process carried out priorto the recording. More particularly, the optimum recording power Pwo(v),the value θ₁ (v) and the power ratio ΔP(v) are defined by the followingcontinuous functions (4), (5) and (6) of the arbitrary linear velocityv. The process carried out by the step S33 corresponds to the functionof the light emission waveform updating computation means.

Pwo(v)=Pwo _(—)8×*sqrt{(v/v _(—)8×)*a+b  (4)

θ₁(v)=θ_(1—)8×*{(v _(—)8×/v)*c+d}  (5)

ΔP(v)=ΔP _(—)8×*(v _(—)8×/v)*e+f}  (6)

[0093] In each of the first through fourth embodiments described above,such as the second embodiment, for example, it may not be possible toalways record the information under the optimum recording conditiondepending on media manufacturer of the optical disk 1 used due todifferences which exist among the media manufacturers, if the value θ₁(v) which prescribes the recording pulse width, the power ratio ΔP(v)and the optimum recording power Pwo(v) depending on the linear velocityv are calculated and set in the same manner for all media manufacturersof the optical disk 1. But according to this fifth embodiment, the mediamanufacturer of the optical disk 1 used is judged based on theidentification code prerecorded on the optical disk 1, and the value θ₁(v) which prescribes the recording pulse width, the power ratio ΔP(v)and the optimum recording power Pwo(v) are respectively calculated bytaking into consideration the coefficients a through f of the judgedmedia manufacturer. The coefficients a through f are preset for each ofthe media manufacturers. As a result, it is possible to appropriatelycope with the differences among the media manufacturers of the opticaldisk 1 which is used by the optical disk unit.

[0094] In this embodiment, even with respect to the same mediamanufacturer, the type of the optical disk 1 used may differ dependingon the case. For example, the same media manufacturer may manufacturecyanin type optical disks and phthalocyanine type optical disks. In sucha case where different types of optical disks of the same mediamanufacturer may be used in the optical disk unit, the information maynot always be recorded under the appropriate recording condition. Insuch a case, the step S31 identifies a type code read from the opticaldisk 1, in addition to identifying the manufacture code of the opticaldisk 1. As a result, it is possible to judge the media manufacturer ofthe optical disk 1 and the type of the optical disk 1.

[0095] Normally, in the case of the optical disk 1 such as the CD-R, thetype code is indicated by a first digit of a frame of thelead-in-start-time recorded in the ATIP, and the cyanin type opticaldisk is indicated when the type code is 0-4, and the phthalocyanine typeoptical disk is indicated when the type code is 5-9. In other words, itis possible to identify whether the type of the optical disk 1 is thecyanin type or the phthalocyanine type. Accordingly, if thelead-in-start-time is 97m27s60f, it can be judged that the optical disk1 is the cyanin type. The step S33 in this case takes into considerationthe different types of the optical disk 1, and performs the calculationsby adding corrections dependent on the arbitrary linear velocity v withrespect to the value θ_(1—)8× which prescribes the optimum recordingpulse width, the optimum power ratio ΔP_(—)8× of the extra pulse and theoptimum recording power Pwo_(—)8× which are set or determined by theprocess carried out prior to the recording. More particularly, theoptimum recording power Pwo(v), the value θ₁ (v) and the power ratioΔP(v) are defined by the following continuous functions (7), (8) and (9)of the arbitrary linear velocity v, where coefficients ε, θ and δ differdepending on the type of the optical disk 1 and may be prestored in amemory such as the ROM 18 and the non-volatile memory 21.

Pwo(v)=Pwo _(—)8×*sqrt{(v/v _(—)8×)*a* ε+b}  (7)

θ₁(v)=θ_(1—)8×*{(v _(—)8×/v)*c*θ+d}  (8)

ΔP(v)=ΔP_(—)8×*{(v _(—)8×/v)*e* δ+f}  (9)

[0096] Therefore, according to this fifth embodiment which also judgesthe type of the optical disk 1, the value θ₁ (v) which prescribes therecording pulse width, the power ratio ΔP(v) and the optimum recordingpower Pwo(v) are calculated by taking into consideration the valueswhich are obtained by multiplying the coefficients ε, θ and δ whichdiffer depending on the type of the optical disk 1 with respect to thecorresponding coefficients a, c and e which are preset for each judgedmedia manufacturer. Consequently, it is possible to appropriately copewith optical disks 1 manufactured by different media manufacturers aswell as different type of optical disks 1.

[0097] Next, a description will be given of a sixth embodiment of theoptical disk unit according to the present invention, by referring toFIG. 11. FIG. 11 is a flow chart for explaining a recording process ofthis sixth embodiment of the optical disk unit. This sixth embodiment ofthe optical disk unit uses a rewritable optical disk 1, such as theCD-RW.

[0098] For example, as indicated in the Orange Book Part III, the OPC ofthe rewritable optical disk 1 such as the CD-RW obtains a modulationfactor m which is given by the following formula (10) while changing thelaser power of the semiconductor laser in multi-steps, where pk and btrespectively denote a peak and a bottom of the read signal amplitude,and further obtains a normalized slope γ which is given by the followingformula (11) based on the modulation factor m and the recording powercharacteristic. The OPC is carried out by obtaining a recording (write)power Pw at which the normalized slope γ becomes γ=γt, where γt is apredetermined value which is peculiar to the optical disk 1.

m=(pk−bt)/pk  (10)

γ=(Δm/ΔPw)*(Pw/m)  (11)

[0099] In addition, instead of using the recording power Pw as it is asthe optimum recording power, it is preferable in some cases to multiplya constant ρ which is peculiar to the optical disk 1 to the recordingpower Pw and to actually use Pw*ρ as the optimum recording power.

[0100] On the other hand, the write strategy with respect to the opticaldisk 1, that is, the CD-RW, uses multi-recording pulses as shown in FIG.3 described above, including a peak pulse width θ₂ and an OFF-pulsewidth xn.

[0101] Under the preconditions described above, when the rewritableoptical disk 1 is loaded into the optical disk unit of this embodimentand a record (write) instruction is received from the host computer, theCPU 17 carries out the functions of a setting means, a test write means,a reference optimum recording power determination means, a recordingrotation control means, a light emission waveform updating computationmeans, and a recording light source control means. FIG. 11 is a flowchart for generally explaining a recording process of this sixthembodiment.

[0102] First, in FIG. 11, when a step S51 issues a record instruction, astep S52 carries out a seek to a predetermined track which is at apredetermined radial position and is within the PCA 31 allocated to theinner peripheral region of the optical disk 1, by controlling theoptical pickup 5 prior to the recording. A step S53 controls the spindlemotor 2 to rotate the optical disk 1 at a predetermined linear velocityin conformance with the CLV system. For example, the predeterminedlinear velocity is v_(—)8×, and the optical disk 1 is rotated at an8-times speed (8×CLV). In this state, a step S54 sets the peak pulsewidth θ₂ and the OFF-pulse width xn for prescribing the write strategyfor the OPC. In other words, the step S54 sets the optimum peak pulsewidth θ_(2—)8× and the OFF-pulse width xn_(—)8× for the predeterminedlinear velocity 8×CLV. Such data which are set are prestored in the ROM18, the non-volatile memory 21 or the like, for example. The processcarried out by the step S54 prior to the recording corresponds to thefunction of the setting means.

[0103] In the state where the write strategy is set in this manner, astep S55 carries out the OPC while rotating the optical disk at thepredetermined linear velocity 8×CLV. That is, the OPC is carried out apredetermined number of times by driving the semiconductor laser at arecording power which differs for each step, while rotating the opticaldisk 1 by the spindle motor 2 at the predetermined linear velocity8×CLV, using the optimum peak pulse width θ_(2—)8× and the OFF-pulsewidth xn_(—)8× for the predetermined linear velocity 8×CLV. The processcarried out by the step S55 prior to the recording corresponds to thefunction of the test write means.

[0104] After the OPC ends, a step S56 reproduces the data recorded bythe test write of the OPC, and detects characteristic values related tothe reproduced data, so as to determine an optimum recording power Pwobased on the characteristic values. In this case, the optimum recordingpower Pwo is Pwo_(—)8×, and the process carried out by the step S56corresponds to the function of the reference optimum recording powerdetermination means.

[0105] After these processes, the actual recording operation is carriedout. More particularly, a step S57 rotates the optical disk 1 by thespindle motor 2 at a predetermined number of revolutions in conformancewith the CAV system. The process carried out by the step S57 correspondsto the function of the recording rotation control means.

[0106] A step S58 successively calculates and sets a peak pulse width θ₂(V), an OFF-pulse width xn(v) and an optimum recording power Pwo(v),depending on an arbitrary linear velocity v at a recording target trackwhich is to be recorded by the optical pickup 5. In many cases, thisarbitrary linear velocity v is greater than the linear velocity v_(—)8×for the PCA 31. The calculations are performed by adding correctionsdependent on the arbitrary linear velocity v with respect to the optimumpeak pulse width θ_(2—)8×, the optimum OFF-pulse width xn_(—)8× and theoptimum recording power Pwo_(—)8× which are set or determined by theprocess carried out prior to the recording. More particularly, theoptimum recording power Pwo(v), the peak pulse width θ₂(v) and theOFF-pulse width xn(v) are defined by the following continuous functions(12), (13) and (14) of the arbitrary linear velocity v. The processcarried out by the step S58 corresponds to the function of the lightemission waveform updating computation means.

Pwo(v)=Pwo _(—)8×*sqrt(v/v _(—)8×)  (12)

θ₂(v)=θ_(2—)8×*(v _(—)8×/v)  (13)

xn(v)=xn _(—)8×*(v _(—)8×/v)  (14)

[0107] A step S59 carries out the recording operation with respect tothe optical disk 1 in conformance with the CAV system, while controllingthe light emission waveform (write strategy) of the semiconductor laservia the laser control circuit 16 based on the peak pulse width θ₂(v),the OFF-pulse width xn(v) and the optimum recording power Pwo(v) whichare successively calculated and updated by the step S58. The processcarried out by the step S59 corresponds to the function of the recordinglight source control means.

[0108] Therefore, according to this embodiment, it is possible toimprove the recording velocity because the optical disk 1 is basicallyrotated at the predetermined number of revolutions in conformance withthe CAV system during the recording. Furthermore, since the peak pulsewidth θ₂(v), the OFF-pulse width xn(v) and the optimum recording powerPwo(v) are successively calculated, and the recording is carried outwhile controlling the light emission waveform of the semiconductor laserbased on the calculated values, it is possible to always record theinformation under a stable recording condition in conformance with theCAV system, even if the linear velocity during the recording changes.

[0109] Next, a description will be given of a seventh embodiment of theoptical disk unit according to the present invention, by referring toFIG. 12. FIG. 12 is a flow chart for explaining a recording process ofthis seventh embodiment of the optical disk unit. In FIG. 12, thosesteps which are the same as those corresponding steps in FIG. 11 aredesignated by the same reference numerals, and a description thereofwill be omitted.

[0110] In the sixth embodiment described above, the operation of theoptical disk unit is always in conformance with the CAV system whilerecording the information. Accordingly, as the target track movestowards the outer periphery of the optical disk 1, the linear velocity vincreases, and the optimum recording power Pwo(v) which is successivelycalculated also increases. For this reason, in a case where therecording sensitivity of the optical disk 1 is low and the optimumrecording power Pwo(v) which is originally determined by the OPC islarge, the optimum recording power Pwo(v) may exceed a predeterminedupper limit, that is, a maximum output Pwmax of the semiconductor laserdepending on the position of the track in the outer peripheral region ofthe optical disk 1. In such a case, the recording cannot be carried outat the optimum recording power Pwo(v).

[0111] This seventh embodiment takes into account such a case. Moreparticularly, during the actual recording operation, a step S60 shown inFIG. 12 decides whether or not the optimum recording power Pwo(v) whichis successively calculated is less than the maximum output Pwmax(predetermined upper limit value) of the semiconductor laser. If thedecision result in the step S60 is YES, a step S61 rotates the opticaldisk 1 in conformance with the CAV system, that is, continues therotation control of the step S57. Then, after the step S61, the step S59carries out the recording operation with respect to the optical disk 1in conformance with the CAV system.

[0112] On the other hand, if the decision result in the step S60 is NO,a step S62 stores the optimum recording power Pwo(v) (=Pwmax) and thepeak pulse width θ₂(v) and the OFF-pulse width xn(v) in this state, asthe write strategy of the semiconductor laser, in order to record on thetracks subsequent to the target track. In addition, a step S63 switchesthe rotation of the spindle motor 2 to rotate the optical disk 1 at thelinear velocity v which becomes constant in this state in conformancewith the CLV system. A step S64 carries out the recording operation withrespect to the optical disk 1 in conformance with the CLV system whilecontrolling the light emission waveform (write strategy) of thesemiconductor laser via the laser control circuit 16, based on thestored optimum recording power Pwo(v) (=Pwmax) and the peak pulse widthθ₂(v) and the OFF-pulse width xn(v) in this state.

[0113] The process carried out by the step S60 corresponds to thefunction of the judging means, and the process carried out by the stepS63 corresponds to the function of the recording rotation control means.The process carried out by the step S64 corresponds to the function ofthe recording light source control means.

[0114] According to this embodiment, a decision is made to determinewhether or not the optimum recording power Pwo(v) reaches the maximumoutput Pwmax of the semiconductor laser. The recording is carried out inconformance with the CAV system at the original predetermined number ofrevolutions in a track region in which the maximum output Pwmax is notexceeded. On the other hand, in a track region in which the maximumoutput Pwmax is reached or exceeded, the recording is carried out inconformance with the CLV system at the constant linear velocity whichintroduces no change in the linear velocity v. For this reason, it ispossible to continue the recording at the maximum output of thesemiconductor laser, and it is thus possible to cope with cases wherethe semiconductor laser used has a low maximum output for the recordingpower and the optical disk used has a low recording sensitivity, by aminimum required decrease in the recording velocity.

[0115] Next, a description will be given of an eighth embodiment of theoptical disk unit according to the present invention, by referring toFIG. 13. FIG. 13 is a flow chart for explaining a recording process ofthis eighth embodiment of the optical disk unit. In FIG. 13, those stepswhich are the same as those corresponding steps in FIG. 11 aredesignated by the same reference numerals, and a description thereofwill be omitted.

[0116] This eighth embodiment is similar to the sixth embodiment, exceptthat this eighth embodiment rotates the optical disk 1 in conformancewith the ZCLV system in place of the CAV system during the recording.For example, the recording surface of the optical disk 1 is divided intoN=4 zones in the radial direction, and the recording is carried out byrotating the optical disk 1 in conformance with the CLV system so thatthat the rotational velocity (linear velocity) successively differs foreach of the zones from the inner periphery towards the outer periphery,as 8×, 12×, 16× and 20×.

[0117] The processes carried out by the steps S51 through S56 prior tothe recording in this eighth embodiment which employs the ZCLV system,are the same as those carried out in the sixth embodiment. In otherwords, the processes such as determination of the optimum recordingpower Pwo by the OPC are carried out once using the PCA 31.

[0118] When the processes carried out prior to the recording end, a stepS71 shown in FIG. 13 carries out a seek to a recording target zone N ofthe optical disk 1 by moving the optical pickup 5, so as to start therecording operation. A step S72 successively calculates and sets thepeak pulse width θ₂ (v), the OFF-pulse width xn(v) and the optimumrecording power Pwo(v), depending on the arbitrary linear velocity vrelated to the recording target zone N which is to be recorded by theoptical pickup 5. The calculations are performed by adding correctionsdependent on the arbitrary linear velocity v with respect to the optimumpeak pulse width θ_(2—)8×, the optimum OFF-pulse width xn_(—)8× and theoptimum recording power Pwo_(—)8× which are set or determined by theprocess carried out prior to the recording. More particularly, theoptimum recording power Pwo(v), the peak pulse width θ₂(v) and theOFF-pulse width xn(v) are defined by the continuous functions (12), (13)and (14) of the arbitrary linear velocity v described above. The processcarried out by the step S72 corresponds to the function of the lightemission waveform updating computation means.

[0119] A step S73 rotates the optical disk 1 by the spindle motor 2 inconformance with the CLV system so that the linear velocity v becomesthe predetermined linear velocity for the zone N. The process carriedout by the step S73 corresponds to the function of the recordingrotation control means.

[0120] A step S74 carries out the recording operation with respect tothe optical disk 1 in conformance with the CLV system, while controllingthe light emission waveform (write strategy) of the semiconductor laservia the laser control circuit 16 based on the peak pulse width θ₂(v),the OFF-pulse width xn(v) and the optimum recording power Pwo(v) whichare successively calculated and updated by the step S72. The processcarried out by the step S74 corresponds to the function of the recordinglight source control means.

[0121] When carrying out the recording by rotating the optical disk 1 inconformance with the ZCLV system, if the process of the sixth embodimentwere carried out with respect to each zone, it would be necessary to setthe peak pulse width θ₂(v) and the OFF-pulse width xn(v) for each of thelinear velocities amounting to the number N of zones, and to determinethe optimum recording power Pwo by the OPC. But according to this eighthembodiment, the setting of the peak pulse width θ₂(v) and the OFF-pulsewidth xn(v) and the determination of the optimum recording power Pwoonly need to be carried out once based on the PCA 31 which has thepredetermined radial position and in which the linear velocity is thepredetermined linear velocity 8×. Thereafter, the peak pulse widthθ₂(V), the OFF-pulse width xn(v) and the optimum recording power Pwo(v)can be successively calculated and set depending on the linear velocityv of the target recording zone, so that it is possible to always recordthe information under a stable recording condition, even with respect tothe ZCLV system.

[0122] Next, a description will be given of a ninth embodiment of theoptical disk unit according to the present invention, by referring toFIG. 14. FIG. 14 is a flow chart for explaining a recording process ofthis ninth embodiment of the optical disk unit. In FIG. 14, those stepswhich are the same as those corresponding steps in FIGS. 11 through 13are designated by the same reference numerals, and a description thereofwill be omitted.

[0123] In the eighth embodiment described above, the optimum recordingpower Pwo(v) calculated based on the continuous function (12) describedabove with respect to the recording zone in which the linear velocity is20×CLV, for example, may exceed the maximum output Pwmax (predeterminedupper limit value) of the semiconductor laser. In other words, it maynot be possible to record at the optimum recording power Pwo(v) in sucha case.

[0124] This ninth embodiment takes such a case into consideration. Moreparticularly, during the actual recording operation, the step S60 shownin FIG. 14 decides whether or not the optimum recording power Pwo(v)which is successively calculated is less than the maximum output Pwmax(predetermined upper limit value) of the semiconductor laser. If thedecision result in the step S60 is YES, the step S73 rotates the opticaldisk 1 in conformance with the ZCLV system, and the step S74 carries outthe recording operation with respect to the optical disk 1 inconformance with the CLV system within the zone.

[0125] On the other hand, if the decision result in the step S60 is NO,the step S62 stores the optimum recording power Pwo(v) (=Pwmax) and thepeak pulse width θ₂(v) and the OFF-pulse width xn(v) in this state, asthe write strategy of the semiconductor laser, in order to record on thezones subsequent to the recording target zone. In addition, a step S75switches the rotation of the spindle motor 2 to rotate the optical disk1 at the linear velocity v which becomes constant in this state inconformance with the CLV system. A step S76 carries out the recordingoperation with respect to the optical disk 1 in conformance with the CLVsystem while controlling the light emission waveform (write strategy) ofthe semiconductor laser via the laser control circuit 16, based on thestored optimum recording power Pwo(v) (=Pwmax) and the peak pulse widthθ₂(v) and the OFF-pulse width xn(v) in this state.

[0126] For example, if the optimum recording power Pwo(v) for the linearvelocity 16×CLV becomes the maximum output Pwmax of the semiconductorlaser, the recording operation with respect to the recording zone inwhich the linear velocity is 20×CLV is carried out by switching thelinear velocity to 16×CLV in the step S75. In addition, the optimumrecording power Pwo(v) is set to the maximum output Pwmax, and the peakpulse width θ₂(v) and the OFF-pulse width xn(v) for the linear velocity16×CLV are set in the step S62. Furthermore, the recording operation iscarried out in conformance with the CLV system by the steps S75 and S76.

[0127] The process carried out by the step S60 corresponds to thefunction of the judging means, and the process carried out by the stepS75 corresponds to the function of the recording rotation control means.The process carried out by the step S76 corresponds to the function ofthe recording light source control means.

[0128] Therefore, according to this embodiment, a decision is made todetermine whether or not the optimum recording power Pwo(v) reaches themaximum output Pwmax of the semiconductor laser. The recording iscarried out in conformance with the CLV system at the originalpredetermined linear velocity in a recording zone region in which themaximum output Pwmax is not exceeded. On the other hand, in a recordingzone region in which the maximum output Pwmax is reached or exceeded,the recording is carried out in conformance with the ZCLV system at theconstant linear velocity which introduces no change in the linearvelocity v within each recording zone. For this reason, it is possibleto continue the recording at the maximum output of the semiconductorlaser, and it is thus possible to cope with cases where thesemiconductor laser used has a low maximum output for the recordingpower and the optical disk used has a low recording sensitivity, by aminimum required decrease in the recording velocity.

[0129] Next, a description will be given of a tenth embodiment of theoptical disk unit according to the present invention, by referring toFIG. 15. FIG. 15 is a flow chart for explaining a recording process ofthis tenth embodiment of the optical disk unit. In FIG. 15, those stepswhich are the same as those corresponding steps in FIG. 12 aredesignated by the same reference numerals, and a description thereofwill be omitted.

[0130] This tenth embodiment takes into consideration a manufacturer ofthe optical disk 1. Further, it is assumed for the sake of conveniencethat the manufacturer of the optical disk 1 is taken into considerationwhen using the seventh embodiment described above. Predeterminedcoefficients, optimum write strategies and the like which differ foreach manufacturer are prestored in a memory such as the ROM 18 and thenon-volatile memory 21 or, are successively updated and stored in thememory.

[0131] Under these preconditions, when the optical disk 1 is loaded intothe optical disk unit, a step S81 shown in FIG. 15 identifies amanufacture code recorded on the optical disk 1 to judge the mediamanufacturer. Normally, in the case of the optical disk 1 such as theCD-RW, a lead-in-start-time recorded in the ATIP of the optical disk 1differs for each media manufacturer, and thus, the media manufacturercan be judged by reading this lead-in-start-time. The process carriedout by the step S81 corresponds to the function of a manufacturerjudging means.

[0132] After the media manufacturer is judged, a step S82 sets a writestrategy corresponding to the judged media manufacturer, by reading thewrite strategy from a write strategy table which stores write strategiesof various media manufacturers, optimized for a predetermined linearvelocity. After the step S82, the process advances to the step S52 andthe subsequent steps of the seventh embodiment described above.

[0133] When carrying out the successively updating and calculatingprocess for the actual recording operation, a step S83 is carried out inplace of the step S58. Basically, the step S83 is similar to the stepS58, but differs in that the calculation is made using coefficientswhich are different for each media manufacturer. In other words, thestep S83 performs the calculations by adding corrections dependent onthe arbitrary linear velocity v and predetermined coefficients a throughf which differ for each media manufacturer, with respect to the optimumpeak pulse width θ2 _(—)8×, the optimum OFF-pulse width xn_(—)8× and theoptimum recording power Pwo_(—)8× which are set or determined by theprocess carried out prior to the recording. More particularly, theoptimum recording power Pwo(v), the peak pulse width θ₂(v) and theOFF-pulse width xn(v) are defined by the following continuous functions(15), (16) and (17) of the arbitrary linear velocity v. The processcarried out by the step S83 corresponds to the function of the lightemission waveform updating computation means.

Pwo(v)Pwo _(—)8×*sqrt{(v/v _(—)8×)*a+b}  (15)

θ₂(v)=θ_(2—)8×*{(v _(—)8×/v)*c+d}  (16)

xn(v)xn_(—)8×*{(v _(—)8×/v)*e+f}  (17)

[0134] In each of the sixth through ninth embodiments described above,such as the seventh embodiment, for example, it may not be possible toalways record the information under the optimum recording conditiondepending on media manufacturer of the optical disk 1 used due todifferences which exist among the media manufacturers, if the peak pulsewidth θ₂(v), the OFF-pulse width xn(v) and the optimum recording powerPwo(v) depending on the linear velocity v are calculated and set in thesame manner for all media manufacturers of the optical disk 1. Butaccording to this tenth embodiment, the media manufacturer of theoptical disk 1 used is judged based on the identification codeprerecorded on the optical disk 1, and the peak pulse width θ₂(v), theOFF-pulse width xn(v) and the optimum recording power Pwo(v) arerespectively calculated by taking into consideration the coefficients athrough f of the judged media manufacturer. The coefficients a through fare preset for each of the media manufacturers. As a result, it ispossible to appropriately cope with the differences among the mediamanufacturers of the optical disk 1 which is used by the optical diskunit.

[0135] In this embodiment, even with respect to the same mediamanufacturer, the type, that is, a pigment layer, of the optical disk 1used may differ depending on the case. In such a case where differenttypes of optical disks of the same media manufacturer may be used in theoptical disk unit, the information may not always be recorded under theappropriate recording condition. In such a case, the step S81 identifiesa type code read from the optical disk 1, in addition to identifying themanufacture code of the optical disk 1. As a result, it is possible tojudge the media manufacturer of the optical disk 1 and the type of theoptical disk 1.

[0136] Normally, in the case of the optical disk 1 such as the CD-RW,the type code is indicated by a first digit of a frame of thelead-in-start-time recorded in the ATIP. In other words, it is possibleto identify the type or, the pigment layer, of the optical disk 1 byreading the ATIP. The step S83 in this case takes into consideration thedifferent types of the optical disk 1, and performs the calculations byadding corrections dependent on the arbitrary linear velocity v withrespect to the optimum peak pulse width θ_(2—)8×, the optimum OFF-pulsewidth xn_(—)8× and the optimum recording power Pwo_(—)8× which are setor determined by the process carried out prior to the recording. Moreparticularly, the optimum recording power Pwo(v), the peak pulse widthθ₂(v) and the OFF-pulse width xn(v) are defined by the followingcontinuous functions (18), (19) and (20) of the arbitrary linearvelocity v, where coefficients ε, η and δ differ depending on the typeof the optical disk 1 and may be prestored in a memory such as the ROM18 and the non-volatile memory 21.

Pwo(v)=Pwo _(—)8×*sqrt{(v/v _(—)8×)*a* ε+b}  (18)

θ₂(v)=θ_(2—8)×*{(v _(—)8×/v)*c*η+d}  (19)

xn(v)=xn _(—)8×*{(v _(—)8×/v)*e*δ+f}  (20)

[0137] Therefore, according to this tenth embodiment which also judgesthe type of the optical disk 1, the peak pulse width θ₂(v), theOFF-pulse width xn(v) and the optimum recording power Pwo(v) arecalculated by taking into consideration the values which are obtained bymultiplying the coefficients ε, η and δ which differ depending on thetype of the optical disk 1 with respect to the correspondingcoefficients a, c and e which are preset for each judged mediamanufacturer. Consequently, it is possible to appropriately cope withoptical disks 1 manufactured by different media manufacturers as well asdifferent type of optical disks 1.

[0138] Further, the present invention is not limited to theseembodiments, but various variations and modifications may be madewithout departing from the scope of the present invention.

What is claimed is:
 1. An optical disk unit comprising: a light sourceirradiating a light beam on a recordable optical disk; rotationallydriving means for rotating the optical disk; setting means forpresetting a value θ₁ which prescribes an optimum recording pulse widthof the light source for a case where the optical disk is rotated at apredetermined linear velocity on a track located at a predeterminedradial position on the optical disk, and an optimum power ratio ΔP of anextra pulse at a leading portion of the recording pulse where power isincreased; test write means for carrying out a test write apredetermined number of times prior to recording, on the track locatedat the predetermined radial position on the optical disk, by driving thelight source at a recording power which differs for each step, whilerotating the optical disk by the rotationally driving means at thepredetermined linear velocity, using the value θ₁ which prescribes theoptimum recording pulse width the optimum power ratio ΔP of the extrapulse which are preset by the setting means; reference optimum recordingpower determination means for reproducing data recorded by the testwrite carried out by the test write means, and determining an optimumrecording power Pwo based on characteristic values of the reproduceddata; recording rotation control means for rotating the optical disk bythe rotationally driving means at a predetermined number of revolutionswhen recording information; light emission waveform updating computationmeans for successively calculating a value θ₁ (v) which prescribes therecording pulse width, a power ratio A P(v) and an optimum recordingpower Pwo(v), depending on an arbitrary linear velocity v at a recordingtarget track which is to be recorded, by adding corrections dependent onthe arbitrary linear velocity v with respect to the value θ₁ whichprescribes the optimum recording pulse width when recording theinformation, the power ratio ΔP and the optimum recording power Pwowhich is determined by the reference optimum recording powerdetermination means; and recording light source control means forrecording the information while controlling a light emission waveform ofthe light source based on the value θ₁ (v) which prescribes therecording pulse width, the power ratio ΔP(v) and the optimum recordingpower Pwo(v) which are successively calculated by the light emissionwaveform update computation means.
 2. The optical disk unit as claimedin claim 1, further comprising: judging means for judging whether or notthe optimum recording power Pwo(v) calculated by the light emissionwaveform update computation means depending on the arbitrary linearvelocity v on the track reaches a predetermined upper limit value of anoutput power of the light source, said recording rotation control meansswitching rotation to rotate the optical disk by the rotationallydriving means at a constant linear velocity in a track region in whichthe judging means judges that the optimum recording power Pwo(v) reachesthe predetermined upper limit value of the output power of the lightsource.
 3. The optical disk unit as claimed in claim 1, furthercomprising: manufacturer judging means for judging a manufacturer of theoptical disk based on an identification code prerecorded on the opticaldisk, said light emission waveform updating computation meanscalculating the value θ₁ (v) which prescribes the recording pulse width,the power ratio ΔP(v) and the optimum recording power Pwo(v), dependingon the arbitrary linear velocity v and coefficients which are preset foreach manufacturer judged by the manufacturer judging means.
 4. Theoptical disk unit as claimed in claim 3, wherein said manufacturerjudging means further judges a type of the optical disk, and said lightemission waveform updating computation means uses for the calculationvalues which are obtained by multiplying constants to corresponding onesof the coefficients depending on the type of the optical disk judged bysaid manufacturer judging means.
 5. An optical disk unit for recordinginformation on a recordable optical disk which has a recording surfacedivided into a plurality of zones in a radial direction thereof, byrotating the optical disk at a rotational velocity which is differentfor each zone so that a linear velocity within each zone isapproximately constant, said optical disk unit comprising: a lightsource irradiating a light beam on the optical disk; rotationallydriving means for rotating the optical disk; setting means forpresetting a value θ₁ which prescribes an optimum recording pulse widthof the light source for a case where the optical disk is rotated at apredetermined linear velocity on a track located at a predeterminedradial position on the optical disk, and an optimum power ratio ΔP of anextra pulse at a leading portion of the recording pulse where power isincreased; test write means for carrying out a test write apredetermined number of times prior to recording, on the track locatedat the predetermined radial position on the optical disk, by driving thelight source at a recording power which differs for each step, whilerotating the optical disk by the rotationally driving means at thepredetermined linear velocity, using the value θ₁ which prescribes theoptimum recording pulse width the optimum power ratio ΔP of the extrapulse which are preset by the setting means; reference optimum recordingpower determination means for reproducing data recorded by the testwrite carried out by the test write means, and determining an optimumrecording power Pwo based on characteristic values of the reproduceddata; recording rotation control means for rotating the optical disk bythe rotationally driving means at a rotational velocity which isdifferent for each zone so that a predetermined linear velocity isapproximately obtained within each zone when recording information;light emission waveform updating computation means for successivelycalculating a value θ₁ (v) which prescribes the recording pulse width, apower ratio ΔP(v) and an optimum recording power Pwo(v), depending on anarbitrary linear velocity v at a recording target zone which is to berecorded, by adding corrections dependent on the arbitrary linearvelocity v with respect to the value θ₁ which prescribes the optimumrecording pulse width when recording the information, the power ratio ΔPand the optimum recording power Pwo which is determined by the referenceoptimum recording power determination means; and recording light sourcecontrol means for recording the information while controlling a lightemission waveform of the light source based on the value θ₁ (v) whichprescribes the recording pulse width, the power ratio ΔP(v) and theoptimum recording power Pwo(v) which are successively calculated by thelight emission waveform update computation means.
 6. The optical diskunit as claimed in claim 5, further comprising: judging means forjudging whether or not the optimum recording power Pwo(v) calculated bythe light emission waveform update computation means depending on thearbitrary linear velocity v on the track reaches a predetermined upperlimit value of an output power of the light source, said recordingrotation control means switching rotation to rotate the optical disk bythe rotationally driving means at a linear velocity with which thepredetermined upper limit value becomes the optimum recording powerPwo(v) in a recording zone region in which the judging means judges thatthe optimum recording power Pwo(v) reaches the predetermined upper limitvalue of the output power of the light source.
 7. The optical disk unitas claimed in claim 5, further comprising: manufacturer judging meansfor judging a manufacturer of the optical disk based on anidentification code prerecorded on the optical disk, said light emissionwaveform updating computation means calculating the value θ₁ (v) whichprescribes the recording pulse width, the power ratio ΔP(v) and theoptimum recording power Pwo(v), depending on the arbitrary linearvelocity v and coefficients which are preset for each manufacturerjudged by the manufacturer judging means.
 8. The optical disk unit asclaimed in claim 7, wherein said manufacturer judging means furtherjudges a type of the optical disk, and said light emission waveformupdating computation means uses for the calculation values which areobtained by multiplying constants to corresponding ones of thecoefficients depending on the type of the optical disk judged by saidmanufacturer judging means.
 9. An optical disk unit comprising: a lightsource irradiating a light beam on a rewritable optical disk;rotationally driving means for rotating the optical disk; setting meansfor presetting an optimum peak pulse width θ₂ at a leading portion ofmulti-recording pulses of the light source and an OFF-pulse width xn ata last portion of the multi-recording pulses for a case where theoptical disk is rotated at a predetermined linear velocity on a tracklocated at a predetermined radial position on the optical disk; testwrite means for carrying out a test write a predetermined number oftimes prior to recording, on the track located at the predeterminedradial position on the optical disk, by driving the light source at arecording power which differs for each step, while rotating the opticaldisk by the rotationally driving means at the predetermined linearvelocity, using the peak pulse width θ₂ and the OFF-pulse width xn whichare preset by the setting means; reference optimum recording powerdetermination means for reproducing data recorded by the test writecarried out by the test write means, and determining an optimumrecording power Pwo based on characteristic values of the reproduceddata; recording rotation control means for rotating the optical disk bythe rotationally driving means at a predetermined number of revolutionswhen recording information; light emission waveform updating computationmeans for successively calculating a peak pulse width θ₂ (v), anOFF-pulse width xn(v) and an optimum recording power Pwo(v), dependingon an arbitrary linear velocity v at a recording target track which isto be recorded, by adding corrections dependent on the arbitrary linearvelocity v with respect to the peak pulse width θ₂, the OFF-pulse widthxn and the optimum recording power Pwo which is determined by thereference optimum recording power determination means; and recordinglight source control means for recording the information whilecontrolling a light emission waveform of the light source based on thepeak pulse width θ₂ (v), the OFF-pulse width xn(v) and the optimumrecording power Pwo(v) which are successively calculated by the lightemission waveform update computation means.
 10. The optical disk unit asclaimed in claim 9, further comprising: judging means for judgingwhether or not the optimum recording power Pwo(v) calculated by thelight emission waveform update computation means depending on thearbitrary linear velocity v on the track reaches a predetermined upperlimit value of an output power of the light source, said recordingrotation control means switching rotation to rotate the optical disk bythe rotationally driving means at a constant linear velocity in a trackregion in which the judging means judges that the optimum recordingpower Pwo(v) reaches the predetermined upper limit value of the outputpower of the light source.
 11. The optical disk unit as claimed in claim9, further comprising: manufacturer judging means for judging amanufacturer of the optical disk based on an identification codeprerecorded on the optical disk, said light emission waveform updatingcomputation means calculating the peak pulse width θ₂ (v), the OFF-pulsewidth xn(v) and the optimum recording power Pwo(v), depending on thearbitrary linear velocity v and coefficients which are preset for eachmanufacturer judged by the manufacturer judging means.
 12. The opticaldisk unit as claimed in claim 11, wherein said manufacturer judgingmeans further judges a type of the optical disk, and said light emissionwaveform updating computation means uses for the calculation valueswhich are obtained by multiplying constants to corresponding ones of thecoefficients depending on the type of the optical disk judged by saidmanufacturer judging means.
 13. An optical disk unit for recordinginformation on a rewritable optical disk which has a recording surfacedivided into a plurality of zones in a radial direction thereof, byrotating the optical disk at a rotational velocity which is differentfor each zone so that a linear velocity within each zone isapproximately constant, said optical disk unit comprising: a lightsource irradiating a light beam on the optical disk; rotationallydriving means for rotating the optical disk; setting means forpresetting a peak pulse width θ₂ at a leading portion of multi-recordingpulses of the light source and an OFF-pulse width xn at a last portionof the multi-recording pulses for a case where the optical disk isrotated at a predetermined linear velocity on a track located at apredetermined radial position on the optical disk; test write means forcarrying out a test write a predetermined number of times prior torecording, on the track located at the predetermined radial position onthe optical disk, by driving the light source at a recording power whichdiffers for each step, while rotating the optical disk by therotationally driving means at the predetermined linear velocity, usingthe peak pulse width θ₂ and the OFF-pulse width xn which are preset bythe setting means; reference optimum recording power determination meansfor reproducing data recorded by the test write carried out by the testwrite means, and determining an optimum recording power Pwo based oncharacteristic values of the reproduced data; recording rotation controlmeans for rotating the optical disk by the rotationally driving means ata rotational velocity which is different for each zone so that apredetermined linear velocity is approximately obtained within each zonewhen recording information; light emission waveform updating computationmeans for successively calculating a peak pulse width θ₂ (v), anOFF-pulse width xn(v) and an optimum recording power Pwo(v), dependingon an arbitrary linear velocity v at a recording target zone which is tobe recorded, by adding corrections dependent on the arbitrary linearvelocity v with respect to the peak pulse width θ₂, the OFF-pulse widthxn and the optimum recording power Pwo which is determined by thereference optimum recording power determination means; and recordinglight source control means for recording the information whilecontrolling a light emission waveform of the light source based on thepeak pulse width θ₂ (v), the OFF-pulse width xn(v) and the optimumrecording power Pwo(v) which are successively calculated by the lightemission waveform update computation means.
 14. The optical disk unit asclaimed in claim 13, further comprising: judging means for judgingwhether or not the optimum recording power Pwo(v) calculated by thelight emission waveform update computation means depending on thearbitrary linear velocity v on the track reaches a predetermined upperlimit value of an output power of the light source, said recordingrotation control means switching rotation to rotate the optical disk bythe rotationally driving means at a linear velocity with which thepredetermined upper limit value becomes the optimum recording powerPwo(v) in a recording zone region in which the judging means judges thatthe optimum recording power Pwo(v) reaches the predetermined upper limitvalue of the output power of the light source.
 15. The optical disk unitas claimed in claim 13, further comprising: manufacturer judging meansfor judging a manufacturer of the optical disk based on anidentification code prerecorded on the optical disk, said light emissionwaveform updating computation means calculating the peak pulse width θ₂(v), the OFF-pulse width xn(v) and the optimum recording power Pwo(v),depending on the arbitrary linear velocity v and coefficients which arepreset for each manufacturer judged by the manufacturer judging means.16. The optical disk unit as claimed in claim 15, wherein saidmanufacturer judging means further judges a type of the optical disk,and said light emission waveform updating computation means uses for thecalculation values which are obtained by multiplying constants tocorresponding ones of the coefficients depending on the type of theoptical disk judged by said manufacturer judging means.